Field of Disclosure
The following relates generally to wireless communication, and more specifically to radio resource management (RRM) based on silent interference measurements in LTE over unlicensed spectrum.
Description of Related Art
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., an LTE system).
By way of example, a wireless multiple-access communications system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UEs). A base station may communicate with the communication devices on downlink channels (e.g., for transmissions from a base station to a UE) and uplink channels (e.g., for transmissions from a UE to a base station).
Wireless communication systems may employ various radio resource management (RRM) techniques. For example, spectrum resources may be assigned by fixed channel allocation (FCA) or dynamic frequency selection (DFS). Cellular networks tend to operate using FCA in licensed frequency bands. DFS may be applied in wireless networks with several adjacent non-centrally controlled access points or devices. DFS may be used by the access points or devices to select frequency channels with low interference levels. DFS is supported by various IEEE 802.11 wireless local area network (WLAN) protocols. DFS may also be mandated in certain frequency bands for avoidance of other transmissions (e.g., radar, etc.). Generally, the process of DFS may also be called channel selection.
With increasing data traffic in cellular networks that use a licensed radio frequency spectrum band, offloading of at least some data traffic to an unlicensed radio frequency spectrum band may provide a cellular operator (e.g., an operator of a public land mobile network (PLMN) or a coordinated set of base stations defining a cellular network, such as an LTE/LTE-A network) with opportunities for enhanced data transmission capacity. Use of an unlicensed radio frequency spectrum band may also provide service in areas where access to a licensed radio frequency spectrum band is unavailable. In some cases, the cellular network my utilize carrier waveforms similar to those used in the multiple access cellular communication system over the unlicensed spectrum. For example, networks may use LTE/LTE-A cells in unlicensed spectrum, which may be known as LTE-Unlicensed (LTE-U) operation. However, performing channel selection for LTE-U cells without causing or receiving substantial interference from other users of the unlicensed spectrum may present challenges.